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From claiming the existence of magical creatures to odd consequences of kids' actions, parents often come up with creative tales to shape a child's behaviors and emotions.

"We are surprised by how often parenting by lying takes place," said study researcher Kang Lee of the University of Toronto, Canada. "Our findings showed that even the parents who most strongly promoted the importance of honesty with their children engaged in parenting by lying."

Lee and colleagues acknowledge that their work is preliminary, bringing to the forefront an issue that is rarely studied. They are not sure the implications of parental lying, but suggest such tall tales could give kids mixed messages at a time when they are trying to figure out how to navigate the social world.

Lies could also harm parent-child bonds, said study researcher Gail Heyman of the University of California, San Diego.

It could even keep children from learning certain rules. "If I am always lying to the child in order to get the child to do X, Y, or Z, then they have never learned why they should do X, Y, or Z," said Victoria Talwar of McGill University in Montreal, who was not involved in the current study. "If it's constantly being used, [lying] may be preventing learning opportunities for the child."

The scientists also acknowledge that it's sometimes okay to be less than truthful with a child, say, telling a fib about how beautiful a scribbled drawing looks. But Heyman urges parents to think through the issues and consider alternatives before resorting to the expedient prevarication.

The research is published in the September issue of the Journal of Moral Education and was supported by a grant from the National Institute of Child Health and Human Development.

The lies we tellTo get the scoop on lyingparents, the researchers ran two studies in which parents and students commented on nine hypothetical scenarios in which a parent lied to a child to either shape behavior or make the kid happy.

For instance, one behavior-molding scenario reads: "A parent is embarrassed by a child's crying and says, 'The police will come to make sure that you behave if you don't stop crying now.'"

Another scenario, aimed at shaping emotions, goes: "A favorite uncle has just died and the child is told that he has become a star to watch over the child." Another emotion-shifter: "A child is told, 'you did a good job at cleaning up your room' after making things messier."

In one study, about 130 undergraduates read each scenario and indicated on a scale from 1 (absolutely no) to 7 (absolutely yes) whether their parents had said something similar to them.

Nearly 90 percent of students gave a positive rating (5 or greater) to at least one of the tales.

Then, the researchers tested the scenarios on nearly 130 parents, mostly moms, asking each participant to indicate whether they had told similar lies. Parents also rated on a scale from 1 (very bad) to 7 (very good) what the parent in each vignette had said. More than 70 percent said they teach their children that lying is unacceptable. Even so, nearly 80 percent of parents indicated they had told at least one similar lie.

Their own examples revealed parental lying went beyond the little white lie in which politeness or the child's best interest was at stake. Parents were fibbing to prevent tantrums or excessive talking, for instance.

Many parents reported telling their children that bad things would happen if they didn't go to bed or eat certain foods. One mother recalled telling her child that if he didn't finish his food he would get pimples all over his face.

Others reported inventing magical creatures, with one parent saying, "We told our daughter that if she wrapped up all her pacifiers like gifts, the 'paci-fairy' would come and give them to children who needed them...I thought it was healthier to get rid of the pacifiers, and it was a way for her to feel proud and special."

Why parents lieParents lie for various reasons, Heyman said, ranging from benefiting the parents themselves (say, lying to keep a child from crying when you head out for dinner) to protecting the child from scary issues, such as lying to a child about a murder in the news.

"Children sometimes behave in ways that are disruptive or are likely to harm their long-term interests," said Heyman. "It is common for parents to try out a range of strategies, including lying, to gain compliance. When parents are juggling the demands of getting through the day, concerns about possible long-term negative consequences to children's beliefs about honesty are not necessarily at the forefront."

Regardless of whether parental lying is justified, Heyman said parents should figure out their policy on it ahead of time.

"Parents often lie on the spur of the moment, and they don't think about what they're saying and how it will affect their child," Heyman told LiveScience. She added, "I think parents should figure it out in advance what their general beliefs are so when it comes to the situation you're working with your beliefs rather than what pops into your head at the moment."